Incendiary device



March 6, 1956 E. B. HERSHBE-RG 2,737,114

INCENDIARY DEVICE Filed Nov. 6, 1944 [NCENDIARY DEVICE Emanuel 3. Hershbcrg, Stoughton, Mass., assignor to the United States of America as represented by the Sec retary of War Application November 6, 1944, Serial No. 562,112

2 Claims. (Cl. 1632-6) This invention relates to an incendiary device and a case that may be used therefor. More particularly, this invention relates to improvements in incendiary bombs that are very effective against residential and industrial targets.

One object of this invention is the provision of a reinforced case which is particularly useful in the construction of incendiary bombs, but which also may find other uses.

A further object of this invention is the provision of an incendiary bomb in which the incendiary effect is produced by long burning jets extending outwardly from the side walls of the bomb.

A further object of this invention is the provision of a bomb which will be projected adjacent a wall or a piece of furniture in a room of a building after it has penetrated the roof thus increasing the probability of the bomb starting an uncontrollable fire.

A still further object of this invention is the provision of an incendiary device having an anti-personnel element associated therewith thus making the bomb and the resulting fire more difiicult to extinguish.

A still further object of this invention is the provision of an incendiary bomb which, on burning, creates a high internal pressure thus forming jets of flame having a farreaching effect.

A further object of this invention is the provision of a bomb wherein a delayed fuze mechanism is positioned adjacent the tail thereof whereby it is less susceptible to damage on impact.

A further object of this invention is the provision of a bomb, having the above indicated characteristics, which is easy to assemble and which may be conveniently clustered for dropping on any desired target.

Further and additional objects will appear from the following description, the accompanying drawing, and the appended claims.

In accordance with one embodiment of this invention, the incendiary device comprises a case of fusible or combustible metal reinforced with a foraminous sheet of a relatively non-fusible, non-combustible metal, an incendiary mixture disposed within the case capable of selfsustained burning at a temperature sufiicient to melt or burn the first mentioned metal, and means for igniting the incendiary mixture. The incendiary mixture that is preferred for use in the device of this invention is that disclosed in a co-pending application, Serial No. 563,352, filed November 14, 1944, by Norman J. Thompson. In that application are described an incendiary mixture and an incendiary device which have been found useful in the construction of incendiaries. This present invention represents, in part, an improvement over the invention disclosed and claimed in this Thompson application.

In accordance with the present invention it has been found that a suitable case may be prepared by casting a combustible or fusible material such as aluminum or magnesium integrally with a reinforcing of a foraminous sheet of a relatively non-fusible, non-combustible metal such as 2,737,114 Fat-exited Mar. 6, 1956 expanded metal, steel wire mesh or perforated sheet steel. In the construction of an incendiary bomb, according to one embodiment of this invention, it is preferred to employ a case wherein the side walls comprise magnesium reinforced with a perforated steel sheet. For example, the perforated steel sheet may be cast integrally with aluminum, or the perforated sheet may be present as an inner or outer lining for magnesium side walls of the case.

An incendiary bomb having the casing indicated above may be filled with an incendiary mixture which is capable of self-sustained burning at a temperature suflicient to burn the magnesium. The ends of the casing are preferably sealed so that hot burning gases will be ejected under pressure from the perforations contained in the reinforcing sheet.

Likewise, it is preferred that the incendiary mixture be capable of producing an ash which will plug up certain of the perforations during burning so that the burning gas jets will primarily be projected from the surface of the bomb adjacent the burning regions. Thus the high pressure of burning vapors finds relief only through a few of the perforations at any one time and accordingly flames of a long-reaching character are formed during the operation of the bomb. This has a tendency markedly to in crease the area within a room in which the bomb will be able to start an uncontrollable fire.

A further feature of the incendiary device of this invention is the provision of means for kicking the bomb into an area within a room where it will be most effective.

This is accomplished by providing a tail for the bomb which is separated from the case by means of an explosive charge detonated a predetermined time after impact. When the tail is blown off the bomb by the explosive charge the burning case is kicked in the opposite direction with sufficient force to strike against a wall or a piece of furniture where it will come to rest.

In addition, the tail piece may be provided with an anti-personnel element such as white phosphorus, a harassing or toxic chemical agent, or a high explosive equipped with a suitable time delay in order to hinder the work of a fire-fighting crew.

For a more complete understanding of this invention reference will now be made to the accompanying drawing wherein:

Fig. 1 is an elevational view of a bomb constructed in accordance with one embodiment of this invention showing the tail piece in its extended position, and

Fig. 2 is an enlarged fragmentary and sectional view of the device shown in Fig. 1.

The bomb shown in the drawing comprises a cast magnesium alloy case 10 having a perforated steel reinforcing sleeve 12 cast integrally therewith. A steel nose piece 14 is secured to one end of the case 10 by means of a steel clamp piece 16 and an incendiary mixture 18 is provided with the reinforced magnesium case i This incendiary mixture is capable of self-sustained burning at a temperature sufficient to burn the magnesium case and may comprise a mixture of thermite, hydrocarbon oil, aluminum, sodium nitrate and sulfur as specified in the co-pending patent application of Norman J. Thompson, Serial No. 563,352, filed November 14, 1944. A solid hydrocarbon core 2 is also disposed within the case 1% and is completely surrounded by the incendiary mixture 13. This solid hydrocarbon core may comprise Gilsonite or any other solid non-volatile hydrocarbon resin or wax-like material. If desired, the hydrocarbon core may be a more or less fluid hydrocarbon of a non-volatile nature suspended in a nitro cellulose or other readily combustible container.

An impact fuze Z2 is mounted in the upper end of the case 10. This fuze comprises a safety plunger 24, a striker 26, a percussion cap 28 and a black powder train 30 in a cylindrical tube 31. The black powder train 30 is arranged to ignite a body of black powder 32 which is capable of igniting the incendiary mixture 18 and of detonating a charge of double base propellant 34 which serves to separate a tail chamber 36 from the case 10 with explosive violence. Adjacent the top of the case 10 is provided an oil proof paper seal 38 over which is secured a perforated steel diaphragm 40. This steel diaphragm is firmly secured to the case 10 to permit considerable pressures to be built up within the case without forcing the diaphragm out of the end thereof.

The tail chamber 36 is secured to the upper end of the case 10 over the perforated steel diaphragm 40. The tail chamber 36 is provided with an end wall 42 spaced from the diaphragm 40 and between which is positioned the double base propellant 34. A black powder tipped fuse 44, a detonator 46 and tetryl pellets 48 are mounted as shown in the end wall 42 and arranged so that the tetryl pellets are fired by the detonator a suitable period after the ignition of the black powder tipped fuse 44 by the double base propellant 34. An anti-personnel agent 37, such as white phosphorus, a vesicant, or a high explosive is contained Within the tail chamber 36.

A extensible tail 50 is mounted on the tail chamber 36 and is arranged to pop out by action of a spring 52 to the extended positions after the bomb has been released from the bomb rack of the airplane or from a suitable cluster.

The function of the above described bomb is as follows:

On release of the bomb from an airplane or from its retaining cluster, the tail piece 50 pops out to the extended position thus providing means for stabilizing the flight of the bomb. At the same time the safety plunger 24 in the fuze 22 is released fully arming the device. On impact of the bomb the striker pin 26, normally spring tensioned away from the percussion cap 28, strikes against the percussion cap and initiates the burning of the powder train 30. After a time normally sufiicient for the bomb to penetrate the superstructure of the target building and come to rest, the powder train ignites the black powder 32. The black powder 32 around the cylinder 31 of fuze 22 in turn ignites the incendiary mixture 18. The incendiary mixture 18 preferably is of the selfsustained burning type and burns leaving a solid ash. As it burns it emits sufircient heat to melt the magnesium case 10 adjacent the burning region and flames are ejected from the perforations in the steel sleeve 12. As the mixture burns downwardly in the bomb case 10 the solid hydrocarbon core is vaporized and cracked and additional burning vapors are ejected under pressure through the perforations in the steel sleeve adjacent the burning region. The ash formed by the burned case and the burned incendiary mixture tends to plug up the perforations in the burned out areas of the bomb and accordingly the pressure built up within the burning bomb is released primarily through those perforations adjacent the burning region with the case. Thus, as the bomb burns down, successive perforations will come into play and the perforations in the burned out areas will tend to become sealed. Of course, the perforations in the bottom region will not be opened up until the mixture has burned down to those regions. Accordingly, it will be clear that an incendiary device has been provided wherein long-reaching flames are ejected through perforations in the side wall of the bomb. The perforations in the diaphragm 40 are also sealed by the ash and the diaphragm is securely fastened to the end of the case to prevent the burning gases from escaping at the top end of the case.

While initiating the burning of the incendiary mixture 18 the black powder at the same time burns through the paper seal 38 and ignites the double base propellant 34 through the perforations in the steel diaphragm 4'0. The double base propellant 34 explodes, separating the tail chamber 36 and the case 10 with such violence that the case 10 is kicked against a side wall, piece of furniture or other object that may be within the room of the target building. Thus the burning of the incendiary mixture in the case 10 continues in a location where it is most apt to start an uncontrollable tire.

The black powder tipped fuse 44 in the tail chamber 36 is ignited by the explosion of the double base propellant 34. This, after a suitable delay, fires the detonator 46 which in turn explodes the tetryl burster pellets 48. The explosive action of these pellets bursts the tail chamber 36, thus liberating an anti-personnel composition which may be white phosphorus, or a vesicant. However, as previously indicated, the tail chamber may be filled with a high explosive capable of being detonated by the tetryl pellets, if desired. This anti-personnel element has a tendency seriously to hinder the action of a fire-fighting crew and increases the probability of the bomb starting an uncontrollable fire.

The tail compartment becomes a particularly useful adjunct of the bomb when it is charged with white phosphorus. The splattering of burning phosphorus in all directions constitutes an effective anti-personnel element, but this is only one of the significant features of the device. The dense smoke affords an effective and persistent screen that makes it diflicult for a fire fighter to locate the burning bomb. The explosion of the compartment occurs with sufficient force to blow out windows and doors in a closed room and thus give the fire access to a supply of air. The burning of the phosphorus increases the overall temperature of the room and thus markedly assists the operation of the bomb proper. This effect may be greatly enhanced if the target area contains any highly inflammable objects such as curtains, paper, cloth covers, etc., even at points remote from the side at which the burning bomb comes to rest. Such objects are often ignited by pieces of phosphorus ejected in the explosion of the tail compartment, and even if these secondary fires may go out, they contribute to the increasing of the temperature of the room and to the fury of a primary conflagration initiated by the burning bomb.

It will be apparent from the foregoing that a highly effective bomb may be produced in accordance with this invention. The bomb is simple to construct, has positive firing characteristics and is particularly adapted readily to start an uncontrollable fire in industrial or residential areas. It will be clear that many modifications may be made without departing from the spirit and scope of this invention. For example, incendiary mixtures other than those specifically disclosed in the co-pending Thompson application may be employed if desired. Likewise the perforated steel sleeve need not be cast integrally with the magnesium case. In fact, in the bomb now contemplated for use, the perforated steel sleeve is separately formed and positioned around the outside of the magnesium case. Likewise other readily fusible or combustible materials may be substituted for the magnesium if desired. Aluminum or other material may be used for this purpose. However, it should be borne in mind that it is desirable to use a substance in the construction of the bomb case which will withstand the high pressures that may be built up therewithin during burning. Likewise, in the construction of the fuse and tail chamber, it will be apparent that other means may be employed for explosively separating the tail chamber from the bomb case. It is therefore intended that this invention be limited only by the scope of the appended claims.

I claim:

1. An incendiary bomb comprising an elongated magnesium case having walls which are relatively thin compared to the interior cross section, a foraminous steel plate substantially coextensive with said magnesium case and in reinforcing relationship thereto, an incendiary mixture disposed wholly within said case, said incendiary mixture including an ash-forming component and a gasforming component and being capable of self-sustained burning at a temperature sufiicient to burn said magnesium, said ash-forming component being of such character as to plug the openings in said foramiuous plate as said burning progresses, a fuse at the tail end of the case for igniting said mixture whereby as burning progresses gases are ejected under pressure primarily from those perforations adjacent the burning region; a tail chamber'secured to said case at the tail end thereof and having a separable connection therewith, a charge of propellant explosive composition positioned between said case and said tail chamber, adapted to be fired by said fuse and arranged, upon firing, to separate said case from said tail chamber, said charge being sufficient to impel said case with considerable velocity but insuflicient to destroy said case, an anti-personnel element positioned within said tail chamber, and a fuse fired by said first mentioned fuse arranged to activate said anti-personnel element a predetermined time after the tail chamber has been separated from said case.

2. An incendiary bomb as defined in claim 1 and further comprising a body of solid hydrocarbon disposed within said incendiary mixture to increase the volume of gas-formed combustion of said mixture.

References Cited in the file of this patent UNITED STATES PATENTS 1,025,500 Wieser et al. May 7, 1912 1,306,747 Chanard June 17, 1919 1,313,068 Chanard Aug. 12, 1919 1,316,005 Vautin Sept, 16, 1919 1,333,786 Thomas Mar. 16, 1920 1,435,228 Hammond Nov. 14, 1922 1,436,248 Hammond Nov. 21, 1922 2,108,019 Neukirch Feb. 8, 1938 2,184,028 Urban Dec. 19, 1939 2,316,656 Walker Apr. 13, 1943 2,318,994 Helmbold May 11, 1943 2,329,522 Duncan Sept. 14, 1943 2,445,311 Cooke et a1. July 20, 1948 

1. AN INCENDIARY BOMB COMPRISING AN ELONGATED MAGNESIUM CASE HAVING WALLS WHICH ATE RELATIVELY THIN COMPARED TO THE INTERIOR CROSS SECTION, A FORAMINOUS STEEL PLATE SUBSTANTIALLY COEXTENSIVE WITH SAID MAGNESIUM CASE AND IN REINFORCING RELATIONSHIP THERETO, AN INCENDIARY MIXTURE DISPOSED, WHOLLY WITHIN SAID CASE, SAID INCENDIARY MIXTURE INCLUDING AN ASH-FORMING COMPONENT AND A GASFORMING COMPONENT AND BEING CAPABLE OF SELF-SUSTAINED BURNING AT A TEMPERATURE SUFFICIENT TO BURN SAID MAGNESIUM, SAID ASH-FORMING COMPONENT BEING OF SUCH CHARACTER AS TO PLUG THE OPENINGS IN SAID FORAMINOUS PLATE AS SAID BURNING PROGRESSES, A FUSE AT THE TAIL END OF THE CASE FOR IGNITING SAID MIXTURE WHEREBY AS BURNING PROGRESSES GASES ARE EJECTED UNDER PRESSURE PRIMARILY FROM THOSE PERFORATIONS ADJACENT THE BURING REGION; A TAIL CHAMBER SECURED TO SAID CASE AT THE TAIL END THEREOF AND HAVING A SEPARABLE CONNECTION THEREWITH, A CHARGE OF PROPELLANT EXPOSIVE COMPOSITION POSITIONED BETWEEN SAID CASE AND SAID TAIL CHAMBER ADAPTED TO BE FIRED BY SAID FUSE AND ARRANGED, UPON FIRING, TO SEPARATE SAID CASE FROM SAID TAIL CHAMBER, SAID CHARGE BEING SUFFICIENT TO IMPEL SAID CASE WITH CONSIDERABLE VELOCITY BUT INSUFFICIENT TO DESTROY SAID CASE, AN ANTI-PERSONNEL ELEMENT POSITIONED WITHIN SAID TAIL CHAMBER, AND A FUSE FIRED BY SAID FIRST MENTIONED FUSE ARRANGED TO ACTIVATE SAID ANTI-PERSONNEL ELEMENT A PREDETERMINED TIME AFTER THE TAIL CHAMBER HAS BEEN SEPARATED FROM SAID CASE. 